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Archive for July, 2010

The increasing number of manufacturers pursuing MBD strategies has resulted in demands for new features and functionality to be added to direct modelers. However, changes to the modeler sometimes result in changes to the data entities (i.e. geometry, attributes, product structure, PMI information and graphical representation) because the new software version is interpreting the model in a different way.
Without a process or tool for confirming the integrity of your CAD data, the data itself begins to pose risks to a number of downstream processes. These risks become greater when automated software updates are invoked by either the PLM system or a user because changes made to the CAD models propagate throughout the entire product/program faster.

Rolling CAD versions not only cause perpetual data instability issues for designers, the situation also impacts simulation, tooling and assembly, and in many cases, production rates. With right improvements, the infusion of a data analysis process after each CAD version roll can help mitigate the weeks or months of troubleshooting that’s likely to follow.

This article offers a snapshot of key risk areas and some examples of how an early warning system can be used to discover, illustrate and document model changes before they implode a master model initiative.

Risks to Product Manufacturing Information (i.e. GD&T)

CAD version updates pose the highest risks to your product manufacturing information because this CAD modeling functionality is new and rapidly evolving. Any change to the PMI information changes the manufacturing definition, which can cause simulation, machining, and product assembly failures, and incurs labor waste associated with troubleshooting and diagnostics.

In this example, our company’s diagnostic tool found PMI changes to the pilot hole annotations in this CAD model:

Risks to Product Shape Definition

Automated CAD version updates forces the system to re-interpret the model. Changing an attribute, adding a feature, and then saving the model can introduce unintentional changes that may not be detected until the model is modified or used by a downstream process. In short, the model is just fine until you save it in the new version.

Risks to Graphical Representation

When you open a CAD model, you are viewing a graphical representation of the geometry, structure, attributes and PMI. Graphical representations may change as the CAD revisions change, which may cause users to make changes to the data because the on-screen representation is inaccurate.

Also, platform changes (i.e. switching from 32-bit to 64-bit platforms) can affect floating point scales, which can also affect how the data is represented on-screen.

Risk Mitigation for CAD Data Stability

One way to mitigate these risks is to automatically detect changes in your product shape, PMI or graphics before your propagate the CAD version roll, and determine the impact to downstream applications.> By using an early detection system, you can remediate these changes and avoid downstream failures, labor waste, and ultimately, production delays.

If your organization would like to learn more about our best practices for detecting, diagnosing, documenting and remediating data stability issues, register for our forty-minute online workshop, “Data Stability for Manufacturing,” by visiting www.transcendata.com or emailing me at jjf@transcendata.com.